I had one fitted. I've also got a dual coil tank, got that done when the plumbing was all done but it's not connected. The more I looked into it, the less I thought it was worth the cost and effort to connect, so it functions on the central heating only. Heating your water and central heating by logs is expensive and if you want to go that way, look at pellet burners. However, unless you have space for a hopper loader, you'll probably find them a real hassle and again, more expensive unless you have a local producer of pellets, clever though.
Brmptonfb has covered it all. My fire was expensive as I needed one certified for a smokless area, so double the price for one and though the liner was cheap, getting it fitted, scaffolding etc, was a fair cost. I wanted another in the kitchen/diner but you can't operate the extractor over the cooker or I couldn't, probably distance dependent.
